Disc-type recording media to which optical reading is applied (hereinafter referred to as “optical discs”), such as DVDs (Digital Versatile Disks) and CDs (Compact Discs), have rapidly become popular for applications of storing computer files and movie streams. Optical discs have a large storage capacity and random accessibility. Unlike contact-type magnetic recording media, there are no concerns regarding wear and damage on a recording surface as a result of reading, head crash, or the like. Furthermore, the disc surface is sturdy, and the risk of data being accidentally deleted is low.
For example, UDF (Universal Disk Format) (registered trademark) established by OSTA (Optical Storage Technology Association) is known as an optical disc format having a high compatibility (for example, refer to Non-Patent Document 1). UDF is an implementation of the ISO/IEC 13346 standard that is also known as ECMA-167 (for example, refer to Non-Patent Document 2) (ISO/IEC 13346, which is a later version of ISO 9660, supports a larger disk capacity and a larger number of files than ISO 9660). In the 1990s, combined with the low price of CD-RW media and CD recorders, the UDF has widely been used for writable optical discs.
Recording and reproduction apparatuses using an optical disc have already been widely used as external recording media and external storage devices for, for example, computers. In recent years, as the recording capacity of disc-type recording media has increased, video cameras of the type that store movies on a disc rather than conventional recording tape have appeared (for example, refer to Patent Document 1).
Since disc-type recording media are random-accessible, it is possible to efficiently find a favorite scene. Also, since access to data is performed in a non-contact manner, it is possible to use media without causing deterioration thereof. For example, the number of users of DVD video cameras has increased year by year from the year 2000 and such cameras have been sold due to the virtues of high image quality and high ease of use, such as editing being possible.
Furthermore, an optical disc standard mainly targeted as applications for video cameras has already been considered. For example, in AVCHD (Advanced Video Coding High Definition), by adding a recording compatibility function and an additional recording compatibility function while appropriately inheriting the contents of the existing disc format standard, a specification regarding the data format for high definition (HD) video cameras or the like has been established.
For example, when a movie stream captured using a video camera is to be coded to an MPEG2-TS stream and recorded, in the case that a clip AV stream (ClipAV Stream) as content data is to be recorded, it is possible to suitably realize a video recording function by using each type of file of a playlist (PlayList) and clip information (ClipInformation). For the movie data, a collection of data, which is a unit necessitating playback for which continuous synchronization playback, that is, real-time playback, is guaranteed, forms one clip (Clip), and is recorded as one movie file. The clip AV stream is a file in which movie streams are stored in an MPEG-TS format. The clip information file exists in a pair with the clip AV stream file, and is a file in which information on a movie stream, which is necessary to reproduce a real movie stream, is described. For the playlist, a play start point (IN point) and a play end point (OUT point) are specified with regard to each of one or more clips, so that the playback section and the playback order of the movie data are specified.
FIG. 13 shows a directory structure defined by AVCHD. “PLAYLIST”, “CLIPINF”, and “STREAM”, which are arranged directly below a BDMV directory are sub-directories for storing playlists, clip information files, and clip AV stream files, respectively. Directories of JAR, JO, and AUXDATA are not required in a video recording function in a VR mode, but are necessary to maintain compatibility with a past file format structure.
Since AVCHD is a new standard, there are no known disc recording apparatuses that are designed to create a directory and a file, which are defined by the AVCHD standard, at the time of an initialization process.
At this point, when a directory defined by the AVCHD standard is not created at the time of an initialization process, at one of timings of processes for recording a user data file, MV/STREAM that is a directory for storing an AV stream file, and MV/CLIPINF and MV/PLAYLIST, which are directories for storing management information on the user data, will be created. However, this poses the following problems.
For example, when, after an instruction for recording an AV stream from a user is accepted, the BDMV directory and the STREAM directory for storing the AV stream file are to be created, in practice, the recording of movie data is not started until the processing is completed, or a buffer for temporarily storing movie data until the processing is completed becomes necessary.
When a write error occurs when these directories are created and a retry process thereof is performed, the time required for the directory creation process can be very long. Until the creation of directories is completed, in the method in which the recording of an AV stream file is not started, the real-time-use capability of the apparatus for a user are considerably deteriorated. Also, in the method of providing a buffer for temporarily storing movie data, a buffer of a very large size becomes necessary.
In the AVCHD standard, with regard to one AV stream file, it is necessary to record corresponding management information files, such as a clip information file and a playlist. After an instruction for stopping the recording of the AV stream is received from the user, when CLIPINF, which is a directory for storing a management information file for the AV stream file, is to be created, the risk of the occurrence of an error due to the write process becomes high. When the creation of the CLIPINF directory fails due to the occurrence of an error, the management information file is not recorded, and it is not possible to reproduce the AV stream in spite of the fact that the AV stream was processed successfully.
Directories of AUXDATA, JO, JAR, and META among the directories defined by the AVCHD are not used in the process for recording user data, such as an AV stream. Therefore, even if there are no such directories, it is possible to record the AV stream file. For example, when these directories are to be created in the process of removing a recording medium from a recording apparatus, the following problems arise.
Initially, when the creation of the directory fails due to an error, in spite of the fact that the user data has been recorded successfully, an invalid state is reached in terms of the AVCHD standard, and there is a risk that the user data cannot be reproduced.
Since each of the directories of AUXDATA, JO, JAR, and META exists directly below the BDMV directory, when AUXDATA, JO, JAR, and META directories are to be created, it is also necessary to update the information on the BDMV directory in a commonly used file system such as UDF. If a write error occurs in the course of this processing and the updating of the BDMV directory fails, a state is reached in which the user data cannot be referred to in spite of the fact that the user data was recorded successfully.
For example, the UDF has meta-information, such as the position of the entity of a file and file attributes as an ICB (Information Control Block) in units of directories and files. The ICB of the directory contains point information for each of FIDs (File Identifier Descriptors) in which the recording position of the ICB regarding a child directory directly below and a file is described. The creation of the AUXDATA, JO, JAR, and META directories directly below the BDMV directory necessitates the creation of an ICB and FIDs, which are the meta-information of each directory of AUXDATA, JO, JAR, and META and also necessitates the updating of the FID of the BDMV directory. For this reason, there is a possibility that a write error occurs when each directory of AUXDATA, JO, JAR, and META is created and also, there is a possibility that a write error occurs when the meta-information of the BDMV directory is updated.
[Patent Document 1]
    Japanese Unexamined Patent Application Publication No. 2004-120364